Tsuyoshi is my best friend.

He is a very strong person.

His strength comes from his mental power.

He underwent an examination of the hard palate.

This mineral is called anhydrite.

He starts biting his nails as soon as he feels stressed.

She is planning a date with her current boyfriend.

He lost everything.

After failing, he blamed himself and was biting his own navel (figuratively expressing deep regret).

He nervously gave my hand a gentle bite.